The invention relates to a method and to a system for producing open or closed annular structural components made of light metal and alloys thereof, preferably magnesium or magnesium alloys, having a two-dimensional or three-dimensional structure by means of extrusion.
In the field of automotive engineering, the space frame concept is known. This type of body construction uses a skeleton composed of closed hollow profiles, which are joined to each other directly or via nodes. By using aluminum or magnesium materials, a reduction in fuel consumption and emissions can be achieved due to weight savings.
EP 0706843 B1 describes a method for producing curved hollow profiles by combining extrusion and bending, and a device for carrying out the method, wherein the hollow profile is bent by a force acting on the workpiece transversely to the extruder, during or immediately after the forming extrusion operation. According to the invention, EP 0706843 B1 describes an intended curving of extruded profiles by way of rounding, using no subsequent hot forming process.
A method for extruding curved profiles is known from U.S. Pat. No. 5,305,625, in which differing frictional resistances on the inner surface of the extrusion die create a local retardation or acceleration of the flow process during extrusion. Due to differing friction conditions, a curved profile exits the die, the profile being guided over a bent discharge section, but not being formed to any greater extent.
A method and a device for producing curved hollow profiles are known from JP-A-03 47815, in which a pressurized gas is trapped inside the hollow profile during the bending operation. A guide member is disposed at a distance from die outlet, wherein the movement of the guide member transversely to the extrusion direction brings about curving of the hollow profile.
Among the known methods for directly rounding an extruded profile upon exiting the die by the exertion of a controlled transverse force so as to bend a profile, creating the necessary contour, poses almost insurmountable technical difficulties, especially in the case of three-dimensional profiles having a variable curvature.
To satisfy the technical requirements, it has already been proposed to shape the contour and the cross-section by way of internal high pressure forming (IHF) of the extruded profile. The disadvantage in this is the enormously high tooling costs.
Furthermore, a method for producing curved (rounded) structural components from an extruded profile, in particular made of aluminum, magnesium or alloys thereof, is known from DE 102 41 028 B3, in which the extruded profile, after exiting the die of the extrusion press, is guided by one or more guide tools for the purpose of being formed into a straight or curved (rounded) profile, and an end section is cut off by a separating tool and fed in the hot state to a hot forming process and to one or more processing stations by way of gripping tools, wherein, prior to the hot forming process or prior to other processing stations, the hot forming temperature is set to the optimal process temperature by cooling the workpiece.